The invention relates to a lamp holder holding a lamp such as a high-intensity discharge lamp and so on, which are used as automotive headlights.
Recent years have seen a tendency to shift from halogen lamps to high-intensity discharge lamps (hereafter, referred as HID) such as metal halide lamps, high-pressure sodium lamps, mercury-vapor lamps and so on in the area of the automobile headlights. There are reasons that the HID has advantage over the halogen lams in having a ray bundle larger, energy efficiency higher and wear characteristics longer than the halogen lamps. Such a discharge lamp-equipped lighting device includes the discharge lamp described above, an igniter performing the instantaneous high-voltage discharge, and a ballast controlling the igniter.
The lamp holder for holding the discharge lamp in the discharge lamp-equipped lighting device has high-voltage side and low-voltage side terminals. An insulating seal member providing electrical isolation between both terminals is disposed between both terminals in order to apply the high-voltage of approximately 30 kV to the lamp.
Concretely, the high-voltage side terminal connected to a high-voltage side of a lamp plug is disposed at a central section of the lamp holder. The low-voltage side terminal connected to a low-voltage side of the lamp plug is disposed at a section close to the outer periphery of the lamp holder. The insulating seal member insulating perfectly and electrically between both terminals is disposed between both terminals. It is possible to increase insulation and withstand voltage performance due to the insulating seal member to obtain a lamp to allow withstanding the high-voltage.
With the lamp, the insulating seal member is simply mated with an outer periphery of a cylindrical guide section enclosing the high-voltage side terminal. Therefore, when the discharge lamp is removed from the lamp holder in order to replace the lamp by new one, there may be cases where the insulating seal member is broken away from the lamp holder with the insulating seal member being adhered to the discharge lamp side. When a new discharge lamp is mounted on the lamp holder without becoming aware of the breakage of the insulating seal member, the new one is mounted on the lamp holder without using the insulating seal member. Therefore, there may be cases where the lighting device sustains damage owing to defective insulation.
To solve such a problem, it is known that another member is added to prevent the insulating seal member from being broken away from the lamp holder on removing the discharge lamp. For example, JP-A-64643/1998 discloses a lamp holder to ensure the fixation of the insulating seal member even when the lamp plug is removed from the lamp holder. With the lamp holder, a section to be equipped with a stopper is arranged at a section to be equipped with high-voltage terminal in order to keep the insulation and withstand voltage performance when a new lamp is mounted. It is possible to prevent the insulating seal member from being removed due to a stopper mounted on the section.
FIG. 1 is a cross sectional view of explaining a structure of preventing the insulating seal member from being removed from the discharge lighting device disclosed in the JP-A-64643/1998 described above. In the drawing, a reference numeral 1 denotes a discharge lamp, a reference numeral 2 denotes a lamp plug of the discharge lamp 1, and a reference numeral 3 denotes a lamp holder having the functions of holding the discharge lamp 1 and of applying power thereto. A reference numeral 4 denotes a high-voltage side terminal for applying the high-voltage to the high-voltage side of the discharge lamp 1, and a reference numeral 5 denotes a low-voltage side terminal connected to the low-voltage side of the discharge lamp 1. A reference numeral 6 denotes a guide section integral with the lamp holder 3 to constitute an outer peripheral wall of the lamp holder 3. The guide section 6 is formed vertically in a fit recess 3a for a lamp plug-fitted purpose. A fit section 2a of the lamp plug 2 includes a central section 2b making contact with the high-voltage side terminal 4, and a peripheral section 2c enclosing the central section 2b and making contact with the low-voltage side terminal 5. An inner peripheral wall 2d of the peripheral section 2c is tapered. A reference numeral 7 denotes an insulating seal member sheathed on the outer periphery of the guide section 6 in order to provide electrical isolation between the high-voltage and low-voltage sides. An outer peripheral wall 7a of the insulating seal member 7 is so reverse-tapered as to allow making contact with the inner peripheral wall 2d of the peripheral section 2c of the lamp plug 2 above. A reference numeral 8 denotes an approximately cylindrical-shaped stopper holding one end of the insulating seal member 7. A circle section 8a of the stopper 8 projects outwardly from the one end of the stopper 8 in a radial direction thereof and makes into contact with an upper end of the guide section 6.
A method of assembling parts will be explained hereafter. The insulating seal member 7 is sheathed on the outer periphery of the guide section 6 of the lamp holder 3 to obtain an assembled unit. The assembled unit is inserted into the lamp holder 3, and then the insulating seal member 7 is held due to the circle section 8a of the stopper 8.
However, since the conventional lamp holder is constituted as described above, it is necessary to add newly parts corresponding to the stopper 8, for example, as another member for preventing the insulating seal member 7 from being removed from the discharge lighting device. The addition of parts leads to not only complicate the structure of the lamp holder to but also increase the cost of manufacturing the lamp holder.
With the conventional lamp holder, the insulating seal member 7 is molded of silicone rubber with flexibility. When the inner peripheral wall 2d of the lamp plug 2 adheres to the outer peripheral wall 7a of the insulating seal member 7 and the discharge lamp 1 is removed from the lamp holder, it is possible to prevent the insulating seal member 7 from being removed therefrom. However, since tear strength of the insulating seal member 7 is weak, the insulating seal member 7 facilitates turning and tearing in part and the correct insulation performance is not kept.
Moreover, with the conventional lamp holder, the guide section 6 is formed at the lamp holder 3 in one piece, and a projected peripheral section of the guide section 6 is higher than the guide section 6. Therefore, there is possibility of impairing the workability of inserting the insulating seal member 7 into the guide section 6.
The invention was made to solve the foregoing problems. Accordingly, it is an object of the invention to provide a lamp holder having a simple structure with improved workability without increasing a parts count. The lamp holder allows reduction of the cost of manufacture, and prevents the insulating seal member adhered to the lamp plug from being broken away from the lamp plug on removing the discharge lamp to replace it by new one. The lamp holder allows to preclude defective insulation caused by dropouts, displacements, entanglement or cracking of the insulating seal member on assembling new parts into the lamp holder, and prevent malfunctions such as damage of the lamp or no-lighting and so on.
In order to achieve the object of the invention, we provide a lamp holder comprising: a fit recess for a lamp plug-fitted purpose; a high-voltage side terminal arranged at any one of a central section of the fit recess and a peripheral section surrounding the central section of the fit recess; a low-voltage side terminal arranged at the other; and an insulation seal member insulating between the low-voltage side terminal and the high-voltage side member, wherein at least one projection is so projected outwardly from an outer peripheral wall of the insulation seal member as to make into contact with an inner peripheral wall of a fit section of the lamp plug side. In this way, it is possible to extensively reduce a contact area between the inner peripheral wall of the fit section of the lamp plug and the insulating seal member. Therefore, when the lamp plug is removed from the lamp holder, it is possible to reduce remarkably the adhesive force and the frictional force between the insulating seal member and the contact face of the inner peripheral wall. Accordingly, it is possible to prevent the insulating seal member from being removed from the lamp holder together with the lamp plug without adding new parts. As a result, it is possible to hold the insulating seal member on the lamp holder with stability.
With the above arrangement, the projection of the insulation seal member may be a rib-shaped rim-projection projected outwardly from the outer peripheral wall of the insulation seal member in a radial direction of the insulation seal member and extending in a peripheral direction. In this way, since the contact area between the inner peripheral wall of the fit section of the lamp plug and the insulating seal member is extensively reduced, the adhesive force and the frictional force between the rim-projection and the contact face can be reduced remarkably. On the other hand, since the whole peripheral wall of the insulating seal member can make into contact with the inner peripheral wall of the fit section of the lamp plug, it is possible to improve insulation seal performance of the lamp holder. Accordingly, it is possible to prevent the insulating seal member from being removed from the lamp holder together with the lamp plug and to improve the insulation performance of the insulating seal member. As a result, it is possible to hold the insulating seal member on the lamp holder with high stability.
With the above arrangement, the projection of the insulation seal member may be a brim-shaped edge-projection projected outwardly from an edge of the insulation seal member in a radial direction of the insulation seal member, the cylindrical fit section of the lamp plug side may press the brim-shaped edge-projection against the fit recess and the outer peripheral wall of the insulation seal member may keep a distance from the inner peripheral wall of the fit section of the lamp plug side. In this way, the outer peripheral wall of the insulating seal member does not make into contact with the inner peripheral wall of the fit section of the lamp plug. Therefore, there is no risk of affixing the outer peripheral wall of the insulating seal member to the inner peripheral wall of the fit section of the lamp plug. Moreover, if the brim-shaped edge projection is affixed to the inner peripheral wall, a frictional force produced between the insulating seal member and a guide section is extremely larger than a peel force produced on peeling the insulating seal member. Therefore, it is possible to prevent the insulating seal member from being removed from the lamp holder together with the lamp plug.
With the above arrangement, the projection of the insulation seal member may include a rim-projection projected outwardly from the outer peripheral wall of the insulation seal member in a radial direction of the insulation seal member and a brim-shaped edge-projection projected outwardly from an edge of the insulation seal member in a radial direction of the insulation seal member, and the cylindrical fit section of the lamp plug side may press the brim-shaped edge-projection against the fit recess. In this way, the outer peripheral wall of the insulating seal member makes into contact with the inner peripheral wall via only the projections arranged at the outer peripheral wall of the insulating seal member. Therefore, if the projections of the outer peripheral wall of the insulating seal member are affixed to the inner peripheral wall, the adhesive force is very weak. Furthermore, the projections are effective to improve insulation performance of the insulating seal member. When the lamp plug is removed from the lamp holder, it is possible to prevent the insulating seal member from being removed from the lamp holder together with the lamp plug. Therefore, it is possible to hold the insulating seal member on the lamp holder with stability without loss of the insulation performance.
With the above arrangement, the rim-projection may be at least one rib extending in a peripheral direction of the insulation seal member. In this way, the outer peripheral wall of the insulating seal member makes into contact with the inner peripheral wall via only a front end of the rim-projection arranged at the outer peripheral wall of the insulating seal member. Therefore, if the rim-projection of the outer peripheral wall of the insulating seal member is affixed to the inner peripheral wall, the adhesive force is very weak. Furthermore, the rim-projection is effective to improve insulation performance of the insulating seal member. When the lamp plug is removed from the lamp holder, it is possible to prevent the insulating seal member from being removed from the lamp holder together with the lamp plug. Therefore, it is possible to hold the insulating seal member on the lamp holder with stability without loss of the insulation performance.
In order to achieve the object of the invention, we provide a lamp holder comprising: a high-voltage side terminal formed at an igniter generating a high voltage in one piece and installed in a socket for allowing insertion of a lamp plug, wherein a secondary side coil of the igniter is connected with a central section of the socket; a low-voltage side terminal connected with a driving circuit in a periphery of the socket; and an insulation seal member insulating between the low-voltage side terminal and the high-voltage side member, wherein a guide section allowing insertion of the insulating seal member is formed integrally at a bobbin constituting a primary and secondary winding of the igniter, and wherein at least one projection is so projected outwardly from an outer peripheral wall of the insulation seal member as to make into contact with an inner peripheral wall of a fit section of the lamp plug side. In this way, we can obtain some effects hereafter. That is, the conventional guide section is formed at the lamp holder in one piece, and further locates at a central recess of the lamp holder. When the insulating seal member is therefore inserted into the guide section, undesired projections are so formed at a periphery of the guide section as to obstruct assembly of the lamp holder. However, with the above arrangement according to the invention, it is possible to assemble the insulating seal member in a step of assembling singly the igniter. It is possible to facilitate the assembly of the insulating seal member because a projection higher than the holder is not formed. In a state of mounting the lamp on the holder, the contact area between the inner peripheral wall of the fit section of the lamp plug and the projections is extensively reduced as compared with the conventional lamp holder. Therefore, it is possible to reduce remarkably the adhesive force or the frictional force between the insulating seal member and the contact face of the inner peripheral wall. Accordingly, it is possible to facilitate assembly of the insulating seal member and to prevent the insulating seal member from being removed from the lamp holder together with the lamp plug without adding new parts. Moreover, it is possible to hold the insulating seal member on the lamp holder with stability.
With the above arrangement, the projection of the insulation seal member may be a rib-shaped rim-projection projected outwardly from the outer peripheral wall of the insulation seal member in a radial direction of the insulation seal member and extending in a peripheral direction. In this way, it is possible to facilitate assembly of the insulating seal member. Since the contact area between the inner peripheral wall of the fit section of the lamp plug and the insulating seal member is extensively reduced, the adhesive force and the frictional force between the rim-projection and the contact face can be reduced remarkably. On the other hand, since the whole peripheral wall of the insulating seal member can make into contact with the inner peripheral wall of the fit section of the lamp plug, it is possible to improve insulation seal performance of the lamp holder. Accordingly, it is possible to prevent the insulating seal member from being removed from the lamp holder together with the lamp plug and to improve the insulation performance of the insulating seal member. As a result, it is possible to hold the insulating seal member on the lamp holder with high stability.
With the above arrangement, the projection of the insulation seal member may be a brim-shaped edge-projection projected outwardly from an edge of the insulation seal member in a radial direction of the insulation seal member, the cylindrical fit section of the lamp plug side may press the brim-shaped edge-projection against the fit recess and the outer peripheral wall of the insulation seal member may keep a distance from the inner peripheral wall of the fit section of the lamp plug side. In this way, the outer peripheral wall of the insulating seal member does not make into contact with the inner peripheral wall of the fit section of the lamp plug. Therefore, there is no risk of affixing the outer peripheral wall of the insulating seal member to the inner peripheral wall of the fit section of the lamp plug. Moreover, if the brim-shaped edge projection is affixed to the inner peripheral wall, a frictional force produced between the insulating seal member and a guide section is extremely larger than a peel force produced on peeling the insulating seal member. Therefore, it is possible to prevent the insulating seal member from being removed from the lamp holder together with the lamp plug.
With the above arrangement, the projection of the insulation seal member may include a rim-projection projected outwardly from the outer peripheral wall of the insulation seal member in a radial direction of the insulation seal member and a brim-shaped edge-projection projected outwardly from an edge of the insulation seal member in a radial direction of the insulation seal member, and the cylindrical fit section of the lamp plug side may press the brim-shaped edge-projection against the fit recess. In this way, it is possible to facilitate assembly of the insulating seal member. Moreover, the outer peripheral wall of the insulating seal member makes into contact with the inner peripheral wall via only the projections arranged at the outer peripheral wall of the insulating seal member. Therefore, if the projections of the outer peripheral wall of the insulating seal member are affixed to the inner peripheral wall, the adhesive force is very weak. Furthermore, the projections are effective to improve insulation performance of the insulating seal member. When the lamp plug is removed from the lamp holder, it is possible to prevent the insulating seal member from being removed from the lamp holder together with the lamp plug. Therefore, it is possible to hold the insulating seal member on the lamp holder with stability without loss of the insulation performance.
With the above arrangement, the rim-projection may be at least one rib extending in a peripheral direction of the insulation seal member. In this way, it is possible to facilitate assembly of the insulating seal member. Moreover, the outer peripheral wall of the insulating seal member makes into contact with the inner peripheral wall via only the rim-projection arranged at the outer peripheral wall of the insulating seal member. Therefore, if the rim-projection of the outer peripheral wall of the insulating seal member is affixed to the inner peripheral wall, the adhesive force is very weak. Furthermore, the rim-projection is effective to improve insulation performance of the insulating seal member. When the lamp plug is removed from the lamp holder, it is possible to prevent the insulating seal member from being removed from the lamp holder together with the lamp plug. Therefore, it is possible to hold the insulating seal member on the lamp holder with stability without loss of the insulation performance.